1. Field of the Invention
The present invention relates to a high resolution positioner, and more particularly to a system for measuring the lateral displacement of one object with respect to another over a moderate distance.
2. Description of the Prior Art
Various applications are known which require relatively precise alignment between objects. For example, laser weapons are known to require relatively precise alignment of components. More particularly, in order to provide relatively high power in a relatively compact configuration, lasers used as laser weapons have been developed with a cylindrical gain volume and an annular ring resonator. Examples of such lasers are disclosed in U.S. Pat. Nos. 4,598,408; 4,744,090; 4,606,036 and 4,516,214. Such lasers are also discussed in commonly owned co-pending patent application concurrently filed herewith Ser. No. 09/176,040. Such high-powered lasers normally include a conical rear reflector, also known as a rear cone, a waxicon, a reflaxicon, a scraper mirror and a plurality of beam steering mirrors forming a compact leg.
As discussed in the aforementioned commonly owned co-pending patent application, it is important that the various components of the cylindrical laser resonator be relatively precisely aligned. However, alignment of such systems is rather complex and must be relatively precisely controlled in order to avoid significant degradation of performance of the laser. For example, in such an application, the alignment of the rear cone relative to beam compactor must be maintained to an accuracy of microns even though the components are separated by four meters. Failure to maintain relatively precise alignment results in what is known as beam walk, which seriously degrades the performance of the laser.
Previous systems for maintaining the alignment of various components of such lasers, are relatively large, cumbersome and are known to be affected by 1/f noise. Thus, there is a need to provide a relatively simple method for measuring the displacement for a relatively high degree of accuracy for objects, such as a beam compactor and a rear cone, separated by as much as about 4 meters.